The XTS movers can be equipped with suitable mechanisms and parts holders - here for the lids - as required.

© Beckhoff Automation

The special feature of the XTS system is that the movers can be grouped as required within the product flow on the lid assembly line, i.e. the processing stations can be approached individually or as a group. Each mover can be controlled individually as its own servo axis, but can also be synchronized with other movers or process sequences if required. Depending on the task, the movers move independently of the absolute position and can also move relative to each other. In this way, they form a flexible buffer from which the individual processing stations can be approached highly dynamically and precisely according to their respective processing performance. In short: In addition to high speed, the XTS offers the necessary flexibility to integrate processing steps that take different lengths of time when preparing, positioning, assembling, testing and ejecting the parts so that cycle times of less than one second can be maintained.

Despite the high complexity of the motion functions, with 34 XTS mover axes alone, a single C6930 IPC (right) is sufficient to control the entire system.

© Beckhoff Automation

As granulate is fed in, the system works with overpressure throughout the entire enclosure, thus avoiding excessive dust and dirt contamination. The entire handling technology - i.e. gripping parts, pushing them up, holding them, pressing them, etc. - is pneumatically controlled via valve terminals. In addition, a belt weigher checks the filling weight during discharge. The entire system is controlled by a control cabinet PC and operated via a 19-inch multi-touch control panel - with CP-Link 4 single-cable connection technology. The XTS data communication takes place via Ethercat, the camera systems are connected via Ethernet TCP/IP. Finally, the Twinsafe safety technology in the form of the EL6900 logic terminal is used in the ultrasonic welding units to implement the corresponding functions, such as emergency stop (STO) and safe shutdown (SS1/SS2).

Michael Müller explains the simple and compact design: "The particular advantage of XTS is that the complete drive and power electronics as well as the position detection are installed in the motor module - i.e. in the XTS rail. This means that only two connection cables lead to the control cabinet - for Ethercat communication and for the 24/48 V supply - saving a lot of space. On a single control cabinet PC, equipped with the Intel quad-core processor Core i7 and the Twincat software, the movers are mapped as servo axes with all the usual motion control functions, such as electronic gears or cams. They can be used to automatically accumulate the workpiece carriers or move them smoothly and limit the centrifugal forces in the curves. Parallelization with a multi-core CPU significantly increases the available computing power compared to sequential processing by one core, so that such an XTS application can be implemented extremely efficiently."

The XTS movers usually enter a station one after the other. However, if the cycle time requires it, multiple stations can also be approached in parallel. For example, if a processing cycle takes longer than one second, the number of processing stations must be doubled, tripled or quadrupled. For example, the ultrasonic welding process takes three to four seconds.

Mechanical effort significantly reduced

Michael Müller, sales manager for special machine construction at Goldfuß, with one of the lids to be assembled.

© Beckhoff Automation

In order to stay within the cycle time, Goldfuß currently uses three ultrasonic welding units. A fourth space is kept free for a possible increase in the cycle time. The situation is similar at the assembly stations. Here, four lids are assembled at the same time. Due to the fast movement of the movers, the machine is therefore independent of the division of the individual stations and adheres exactly to the cycle time. This enables an output rate of 60 parts per minute to be achieved. The fast camera station delivers its result in less than a second, so it is only needed once and is approached by each mover.

Michael Müller summarizes the advantages of the new solution for workpiece carrier transport: "Compared to conventional systems, XTS requires fewer components, which significantly reduces the mechanical complexity. With the system, we can also optimize the movement profiles with cycle time precision and are independent of the division of the various processing stations. In addition, modules can be exchanged, modified or added without great effort if new product requirements arise. The mechanical changes are minimal, as the actual adaptation is carried out by software. After all, the machine has such a modular design that we will be able to use the same concept to serve other requirements and industries in the future."

Author:
Frank Würthner works in industry management for packaging technology at Beckhoff Automation.